This invention relates to alarm signaling between endpoints of a telephone line or trunk, and more specifically to a method of aggregating alarm conditions of plural ones of such telephone lines or trunks and using the aggregated alarm for reporting, logging, maintenance and/or re-routing purposes.
Voice T1/E1 connections include wires carrying data representing voice signals. A normal voice T1 connection, for example, may be used for direct connection to a standard PBX. Such typically would carry a fixed set of twenty-four digitized voice channels (thirty for the higher-bandwidth E1 connection) with each channel having its own allotted, fixed xe2x80x9ctimeslotxe2x80x9d with one byte of digitized voice being transmitted for each channel in turn. The allocation is fixed, so that even when there is no active telephone call in progress, the voice channel bandwidth is unavailable for other purposes. Such voice T1/E1 connections are sometimes referred to as xe2x80x9cchannelizedxe2x80x9d T1/E1 connections. Accordingly, the present invention relates to T1/E1 connections used to directly carry telephone voice signals to a PBX in a conventional time-division-multiplex (TDM) manner.
Signaling among endpoints of such trunks may be in accordance with international standards such as the FRF.11 specification promulgated by the Frame Relay Forum and the ATM AAL2 specification promulgated by the ATM Forum. The FRF.11 specification provides a mechanism for line or trunk state signaling. It does so by reserving an alarm indication signal (AIS) bit for alarm signaling associated with a given endpoint of a single voice bearer VoFR channel. The FRF.11 specification contains no suggestion how an alarm condition might be defined or used in a network application.
In a T1/E1 telephony voice network having at least two connectable endpoint nodes, e.g. PBXs, with a trunk therebetween and a trunking alarm associated with each endpoint node, an alarm aggregation method is proposed. The method involves first detecting a trunking alarm associated with one of the endpoint nodes and second detecting a second trunking alarm associated with another of the endpoint nodes. The results of the first and second detecting are aggregated to determine a condition of the trunk between the at least two connectable endpoint nodes. Preferably, the first aggregating includes performing a logic combination of the results of the first and second detecting. The method may further involve signaling a determined out-of-service condition of the trunk onto an outgoing T1/E1 connection coupled with the affected trunk. Preferably, plural connectable endpoint node pairs define plural ones of such trunks therebetween with each of the plural trunks having a trunking alarm associated with each endpoint node pair. In such a case, the first and second detecting and the first aggregating are performed for each of the plural trunks and the method further involves second aggregating the plural results of the plural instances of the first aggregating. This enables a determination of a condition of the plural trunks between the plural connectable endpoint node pairs.
The invented apparatus is for alarm aggregation and conditioning of a voice T1/E1 connection. The apparatus preferably includes a trunk group including plural dedicated endpoint node pair connections, each endpoint node pair connection including a bi-directional alarm signaling mechanism, the trunk group generating one or more alarms from each alarm signaling mechanism. The apparatus further includes an alarm aggregation mechanism coupled with the trunk group for aggregating one or more alarms generated by the trunk group into a trunk group alarm representing the condition of the trunk group.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment which proceeds with reference to the drawings.